inline terminal emulator, drop xterm.dart dependency

Replace the xterm pub.dev package with owned code under
lib/src/terminal/. Based on xterm.dart v4.0.0 by xuty (MIT).
Quiver LRU replaced with hand-rolled LinkedHashMap cache.
Scrollable removed from TerminalView — scroll events are forwarded
via Listener.onPointerSignal instead. zmodem, debugger, and
suggestion modules stripped as unused.

Also: bundle clide.tmux.conf (no status bar, 50k scrollback,
mouse on, zero escape delay, isolated -L clide socket), bump PTY
read buffer to 64KB, add 2px terminal padding, drop bold
JetBrains Mono registration.

Co-Authored-By: Claude <noreply@anthropic.com>

pubspec.yaml

@@ -37,8 +37,6 @@ dependencies:
 
   yaml: 3.1.3
 
-  xterm: 4.0.0
-
   ffi: 2.1.3
 
   jovial_svg: 1.1.26
@@ -74,6 +72,7 @@ flutter:
     - assets/logo/logo-192.png
     - assets/logo/appicon.svg
     - assets/logo/appicon-256.png
+    - assets/clide.tmux.conf
     - assets/grammars/
     - assets/queries/
 
@@ -96,8 +95,3 @@ flutter:
         - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Regular.ttf
         - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Italic.ttf
           style: italic
-        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-Bold.ttf
-          weight: 700
-        - asset: assets/fonts/jetbrains_mono/JetBrainsMono-BoldItalic.ttf
-          weight: 700
-          style: italic